From: Mike Kravetz <mike.kravetz@oracle.com>
To: kernel test robot <oliver.sang@intel.com>
Cc: oe-lkp@lists.linux.dev, lkp@intel.com,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Ackerley Tng <ackerleytng@google.com>,
Erdem Aktas <erdemaktas@google.com>,
Matthew Wilcox <willy@infradead.org>,
Muchun Song <songmuchun@bytedance.com>,
Sidhartha Kumar <sidhartha.kumar@oracle.com>,
Vishal Annapurve <vannapurve@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-fsdevel@vger.kernel.org, ying.huang@intel.com,
feng.tang@intel.com, fengwei.yin@intel.com
Subject: Re: [linus:master] [page cache] 9425c591e0: vm-scalability.throughput -20.0% regression
Date: Wed, 21 Jun 2023 08:28:54 -0700 [thread overview]
Message-ID: <20230621152854.GA4155@monkey> (raw)
In-Reply-To: <202306211346.1e9ff03e-oliver.sang@intel.com>
On 06/21/23 15:19, kernel test robot wrote:
>
>
> Hello,
>
> kernel test robot noticed a -20.0% regression of vm-scalability.throughput on:
>
>
> commit: 9425c591e06a9ab27a145ba655fb50532cf0bcc9 ("page cache: fix page_cache_next/prev_miss off by one")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> testcase: vm-scalability
> test machine: 96 threads 2 sockets Intel(R) Xeon(R) Platinum 8260L CPU @ 2.40GHz (Cascade Lake) with 128G memory
> parameters:
>
> runtime: 300s
> test: lru-file-readonce
> cpufreq_governor: performance
>
> test-description: The motivation behind this suite is to exercise functions and regions of the mm/ of the Linux kernel which are of interest to us.
> test-url: https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/
>
> In addition to that, the commit also has significant impact on the following tests:
>
> +------------------+----------------------------------------------------------------------------------------------------+
> | testcase: change | vm-scalability: vm-scalability.throughput -18.9% regression |
> | test machine | 96 threads 2 sockets Intel(R) Xeon(R) Platinum 8260L CPU @ 2.40GHz (Cascade Lake) with 128G memory |
> | test parameters | cpufreq_governor=performance |
> | | debug-setup=no-monitor |
> | | runtime=300s |
> | | test=lru-file-readonce |
> +------------------+----------------------------------------------------------------------------------------------------+
> | testcase: change | vm-scalability: vm-scalability.throughput -52.8% regression |
> | test machine | 224 threads 2 sockets Intel(R) Xeon(R) Platinum 8480CTDX (Sapphire Rapids) with 256G memory |
> | test parameters | cpufreq_governor=performance |
> | | runtime=300s |
> | | test=lru-file-readonce |
> +------------------+----------------------------------------------------------------------------------------------------+
> | testcase: change | vm-scalability: vm-scalability.throughput -54.0% regression |
> | test machine | 224 threads 2 sockets Intel(R) Xeon(R) Platinum 8480CTDX (Sapphire Rapids) with 256G memory |
> | test parameters | cpufreq_governor=performance |
> | | debug-setup=no-monitor |
> | | runtime=300s |
> | | test=lru-file-readonce |
> +------------------+----------------------------------------------------------------------------------------------------+
>
Ouch!
I suspected this change could impact page_cache_next/prev_miss users, but had
no idea how much.
Unless someone sees something wrong in 9425c591e06a, the best approach
might be to revert and then add a simple interface to check for 'folio at
a given index in the cache' as suggested by Ackerley Tng.
https://lore.kernel.org/linux-mm/98624c2f481966492b4eb8272aef747790229b73.1683069252.git.ackerleytng@google.com/
--
Mike Kravetz
next prev parent reply other threads:[~2023-06-21 15:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 7:19 [linus:master] [page cache] 9425c591e0: vm-scalability.throughput -20.0% regression kernel test robot
2023-06-21 15:28 ` Mike Kravetz [this message]
2023-06-26 9:05 ` Yin, Fengwei
2023-06-27 4:38 ` Yin Fengwei
2023-06-23 12:36 ` Linux regression tracking #adding (Thorsten Leemhuis)
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